Mississippi legislators are expected to pass a bill that cracks down on illegal immigration, and a federal appeals court will consider whether similar laws in Alabama and Georgia are constitutional.

Reporting from Atlanta — The Deep South, already the nation's hottest illegal immigration battleground, will see more action in the coming days, with Mississippi considering an Alabama-style immigration crackdown bill and a federal appeals court set to consider Thursday whether the Alabama law, and a similar one in Georgia, are constitutional.

The legislation and the courtroom battle will serve as a prelude to April 25, when the Supreme Court will hear oral arguments over Arizona's SB 1070, the controversial 2010 law that triggered a wave of state-level efforts nationwide to get tough on illegal immigrants.

A ruling from the high court will probably give some guidance on how vigorous states can be in tackling immigration, a realm of policy that has traditionally been the bailiwick of the federal government.

But in Mississippi, proponents of the bill see no reason to wait on the justices for guidance. Rodney Hunt, who heads the group Mississippi Federation for Immigration Reform and Enforcement, said the law was needed as soon as possible to help bring down the state's 10.4% unemployment rate.

Republicans in neighboring Alabama have argued that their state's law, which took effect in September, was a key reason the state had the most dramatic unemployment rate reduction in the nation in the last months of 2011, as undocumented workers left the state or otherwise dropped out of the workforce.

"I just think you should not sit back and wait when the citizens want protection," Hunt said.

Passage of the bill in Mississippi, which is likely given Republican control of the Legislature and governor's office, would create a contiguous four-state swath of the South — including Alabama, Georgia and South Carolina — with Arizona-style laws on the books.

Like similar immigration laws in Utah and Indiana, all of the Deep South laws have been challenged and temporarily blocked, in whole or in part, by federal judges.

In Alabama, however, important provisions of the law were upheld in September by U.S. District Judge Sharon Blackburn, including a section that empowers police to check the residency status of suspected illegal immigrants.

Opponents of the laws have accused Southern lawmakers of racism and xenophobia, but the fate of the measures may turn on more complicated arguments about the states' proper role in handling immigration-related matters.

On Thursday in Atlanta, a three-judge panel of the U.S. 11th Circuit Court of Appeals will hear oral arguments against the Alabama law by the Justice Department and lawyers for a coalition of civil rights groups, which sued separately to block the law.

In court documents, Justice Department attorneys argue that the Constitution gives federal authorities the power to regulate immigration and that sections of the Alabama law infringe on that authority.

The Alabama attorney general, Luther Strange, has argued that although the Supreme Court has ruled that the federal government has exclusive control over who may enter the country, states have the authority to address problems created by illegal immigrants once they are here.

The proper role of the state in setting immigration policy is also at the heart of the argument over the Georgia law, which, among other things, criminalizes the transportation or harboring of illegal immigrants.

The decision by the 11th Circuit judges won't directly affect Mississippi, which lies outside their jurisdiction. Still, legislators there are watching the court closely.

Mississippi state Rep. Andy Gipson, a co-sponsor of the bill, said that lawmakers decided to cut out some provisions, including a section that criminalizes a failure to carry immigration papers, because the 11th Circuit temporarily blocked a similar section of Alabama's bill in October.